[рони]

Alexprom,
или совсем скрыт )))

document.addEventListener('DOMContentLoaded', function() {
            let panel = document.querySelector('#oct-slide-panel-mobile');
            const lazyShow = btns => {
                btns.forEach(({intersectionRatio})  => {
                    panel.classList.toggle('show', intersectionRatio == 0);
                });
            };
            let observer = new IntersectionObserver(lazyShow, {
                rootMargin: "0px",
                threshold: [0]
            });
            document.querySelectorAll('.btn').forEach(elem => observer.observe(elem));
       });